Fluoropolymers, such as PTFE have been heretofore used for the manufacture of various types of prosthetic vascular grafts. Among these are various vascular grafts having tubular configurations so that they may be utilized to replace an excised segment of blood vessel.
The tubular prosthetic vascular grafts have traditionally been implanted, by open surgical techniques, whereby a diseased or damaged segment of blood vessel is surgically excised and removed, and the tubular bioprosthetic graft is then anastomosed into the host blood vessel as a replacement for the previously removed segment thereof. Alternatively, such tubular prosthetic vascular grafts have also been used as bypass grafts wherein opposite ends of the graft are sutured to a host blood vessel so as to form a bypass conduit around a diseased, injured or occluded segment of the host vessel.
More recently, methods have been developed for endovascular implantation of tubular prosthetic vascular grafts. Such endovascular implantation initially involves translumenal delivery of the graft, in a compacted state, through a catheter or other delivery apparatus. Thereafter, the graft undergoes in situ expansion and affixation at its intended site of implantation within the host blood vessel. An affixation apparatus is typically utilized to affix the opposite ends of the tubular graft to the surrounding blood vessel wall. In this regard, the endovascularly implanted tubular graft may be utilized to repair an aneurismic segment of a host blood vessel, without requiring open surgical dissection of the host blood vessel.
In general, many of the tubular prosthetic vascular grafts of the prior art have been formed of extruded, porous PTFE tubes. In some of the tubular grafts of the prior art a tape, formed of PTFE film is wrapped about and laminated to the outer surface of a tubular base graft to provide reinforcement and additional burst strength. Also, some of the prior tubular prosthetic vascular grafts have included external support member(s), such as a PTFE beading, bonded or laminated to the outer surface of the tubular graft to prevent the graft from becoming compressed or kinked during implantation. These externally supported tubular vascular grafts have proven to be particularly useful for replacing segments of blood vessel which pass through, or over, joints or other regions of the body which undergo frequent articulation or movement.
One commercially available, externally-supported, tubular vascular graft is formed of a regular walled PTFE tube having a PTFE filament helically wrapped around, and bonded to, the outer surface of the PTFE tube. (IMPRA Flex.TM. Graft, IMPRA, Inc., Tempe, Ariz.)
One other commercially available, externally-supported, tubular vascular graft comprises a regular walled, PTFE tube which has PTFE reinforcement tape helically wrapped around, and bonded to, the outer surface of the PTFE tube and individual rings of Fluorinated Ethylene Propylene (FEP) rings disposed around, and bonded to, the outer surface of the reinforcement tape. (FEP ringed ePTFE vascular graft, W. L. Gore & Associates, Inc., Flagstaff, Ariz.)
When surgically implanting the externally-supported tubular vascular grafts of the prior art, it is typical for the surgeon to peel the support filament or support ring(s) away from the opposite ends of the tubular graft to facilitate anastomosis of the ends of the graft to the host blood vessel. However, such peeling away of the external support filament or ring(s) may, in at least some cases, also result in some peeling or fraying of any reinforcement tape from the adjacent end portions of the tubular graft. Such fraying or peeling of the reinforcement tape concurrently with removal of the external support member(s) is undesirable.
Accordingly, there remains a need in the art for the development of new externally-supported, tape-reinforced, tubular vascular grafts which are constructed to permit an external support member (e.g., a PTFE filament) to be peeled away from the end regions of the graft, without causing concurrent peeling or fraying of the underlying reinforcement tape from the tubular base graft.